EXPRESSION OF SEVERAL GENES ENCODING CHAPERONE PROTEINS IN RESPONSE TO MECHANICAL PERTURBATION IN BRYONIA-DIOICA INTERNODES

Mechanical stress exerted on young Bryonia dioica internodes which res ulted in reduced elongation and increased radial expansion induced a r apid and transient increase in specific mRNAs. Hybridizations were per formed using ubiquitin, cyclophilin and heat-shock protein cDNAs as pr obes on RNA extracted at successive time intervals in control and rubb ed intermodes. Changes in ubiquitin and cyclophilin were rapidly enhan ced after mechanical perturbation. Levels of mRNAs reached a maximum 0 .5 h and 1.5 h after rubbing and then decreased. The heat shock protei n gene was constitutively expressed; it was however slightly stimulate d following the rubbing treatment. All the three genes encoded for mol ecular chaperones and they were regulated in response to environmental stimuli. The role of chaperones was discussed with regard to the plan t response to several natural stresses.